The present invention relates to devices for sensing the direction of rotation of a hand tool comprising an electric motor.
More particularly, the present invention relates to a device for sensing the direction of rotation of a hand tool comprising an electric motor, in particular a rotary hammer or impact drill. The electric motor includes a rotatably supported brush plate which is located in different positions depending on the direction of rotation of the electric motor. The different positions are sensed using at least one sensor to determine the direction of rotation.
Devices of the type described initially are known. For example, there are rotary hammers and impact drills with an electric motor which includes a rotatable brush plate which serves to change the direction of rotation. In addition to increasing the service life of the carbon brushes of the electric motor, this results in optimal commutation and identical values for rotational speed and torque in right and left rotation. Compared with similar hand tools without a rotatable brush plate, the advantage results here, e.g., that screws which were screwed down using the electric hand tool can also be removed using the same hand tool.
To provide information about the direction of rotation of the electric motor, limit switches are installed in modern systems, which forward information about the position of the rotatable brush plate to the electronics. A device of this type requires complex engineering to manufacture, and certain tolerances must be very narrow in order to ensure functionality.